H. L. Falsetti, M. S. Verani, C. J. Chen, and J. A. Cramer, Regional pressure differences in the left ventricle, Cathet. Cardiovasc. Diagn, vol.6, pp.123-134, 1980.

A. Pasipoularides, J. P. Murgo, J. W. Miller, and W. E. Craig, Nonobstructive left ventricular ejection pressure gradients in man, Circ. Res, vol.61, pp.220-227, 1987.

M. Courtois, S. J. Kovács, and P. A. Ludbrook, Transmitral pressure-flow velocity relation. Importance of regional pressure gradients in the left ventricle during diastole, Circulation, vol.78, pp.661-671, 1988.

A. Pasipoularides, Clinical assessment of ventricular ejection dynamics with and without outflow obstruction, J. Am. Coll. Cardiol, vol.15, pp.859-882, 1990.

K. Steine, M. Stugaard, and O. Smiseth, Mechanisms of diastolic intraventricular regional pressure differences and flow in the inflow and outflow tracts, J. Am. Coll. Cardiol, vol.40, pp.983-990, 2002.

M. Courtois, S. J. Kovács, and P. A. Ludbrook, Physiological early diastolic intraventricular pressure gradient is lost during acute myocardial ischemia, Circulation, vol.81, pp.1688-1696, 1990.

N. L. Greenberg, P. M. Vandervoort, and J. D. Thomas, Estimation of Diastolic Intraventricular Pressure Gradients from Color Doppler M-mode Spatiotemporal Velocities: Analytical Euler Equation Solution, Comput Cardiol, pp.465-468, 1994.

N. L. Greenberg, P. M. Vandervoort, and J. D. Thomas, Instantaneous diastolic transmitral pressure differences from color Doppler M mode echocardiography, Am. J. Physiol, vol.271, pp.1267-1276, 1996.

M. S. Firstenberg, Noninvasive estimation of transmitral pressure drop across the normal mitral valve in humans: importance of convective and inertial forces during left ventricular filling, J. Am. Coll. Cardiol, vol.36, pp.1942-1949, 2000.

N. L. Greenberg, P. M. Vandervoort, M. S. Firstenberg, M. J. Garcia, and J. D. Thomas, Estimation of diastolic intraventricular pressure gradients by Doppler M-mode echocardiography, Am. J. Physiol. Heart Circ. Physiol, vol.280, pp.2507-2515, 2001.

J. Bermejo, J. C. Antoranz, R. Yotti, M. Moreno, and M. A. García-fernández, Spatio-temporal mapping of intracardiac pressure gradients. A solution to Euler's equation from digital postprocessing of color Doppler M-mode echocardiograms, Ultrasound Med. Biol, vol.27, pp.621-630, 2001.

A. Rovner, Improvement in diastolic intraventricular pressure gradients in patients with HOCM after ethanol septal reduction, Am. J. Physiol. Heart Circ. Physiol, vol.285, pp.2492-2499, 2003.

R. Yotti, Noninvasive assessment of ejection intraventricular pressure gradients, J. Am. Coll. Cardiol, vol.43, pp.1654-1662, 2004.

R. Yotti, Doppler-derived ejection intraventricular pressure gradients provide a reliable assessment of left ventricular systolic chamber function, Circulation, vol.112, pp.1771-1779, 2005.

M. S. Firstenberg, N. L. Greenberg, M. J. Garcia, and J. D. Thomas, Relationship between ventricular contractility and early diastolic intraventricular pressure gradients: a diastolic link to systolic function, J. Am. Soc. Echocardiogr. Off. Publ. Am. Soc. Echocardiogr, vol.21, pp.501-506, 2008.

R. Yotti, Noninvasive estimation of the rate of relaxation by the analysis of intraventricular pressure gradients, Circ. Cardiovasc. Imaging, vol.4, pp.94-104, 2011.

R. Yotti, A noninvasive method for assessing impaired diastolic suction in patients with dilated cardiomyopathy, Circulation, vol.112, pp.2921-2929, 2005.

A. Rovner, N. L. Greenberg, J. D. Thomas, and M. J. Garcia, Relationship of diastolic intraventricular pressure gradients and aerobic capacity in patients with diastolic heart failure, Am. J. Physiol. Heart Circ. Physiol, vol.289, pp.2081-2088, 2005.

T. Ohara, Loss of adrenergic augmentation of diastolic intra-LV pressure difference in patients with diastolic dysfunction: evaluation by color M-mode echocardiography, JACC Cardiovasc. Imaging, vol.5, pp.861-870, 2012.

H. Iwano, Altered spatial distribution of the diastolic left ventricular pressure difference in heart failure, J. Am. Soc. Echocardiogr. Off. Publ. Am. Soc. Echocardiogr, vol.28, 2015.

J. L. Rojo-alvarez, Impact of image spatial, temporal, and velocity resolutions on cardiovascular indices derived from color-Doppler echocardiography, Med. Image Anal, vol.11, pp.513-525, 2007.

J. M. Bland and D. G. Altman, Statistical methods for assessing agreement between two methods of clinical measurement, Lancet Lond. Engl, vol.1, pp.307-310, 1986.

L. I. Lin, A concordance correlation coefficient to evaluate reproducibility, Biometrics, vol.45, pp.255-268, 1989.

S. F. Nagueh, Recommendations for the Evaluation of Left Ventricular Diastolic Function by Echocardiography: An Update from the American Society of Echocardiography and the European Association of Cardiovascular Imaging, Eur. Heart J. Cardiovasc. Imaging, vol.17, pp.1321-1360, 2016.

J. D'hooge, Two-dimensional speckle tracking echocardiography: standardization efforts based on synthetic ultrasound data, Eur. Heart J. Cardiovasc. Imaging, vol.17, pp.693-701, 2016.

G. Pedrizzetti, G. La-canna, O. Alfieri, and G. Tonti, The vortex-an early predictor of cardiovascular outcome?, Nat. Rev. Cardiol, vol.11, pp.545-553, 2014.